Abstract. Al-Abbawy DAH, Al-Thahaibawi BMH, Al-Mayaly IKA, Younis KH. 2021. Assessment of some heavy metals in various aquatic plants of Al-Hawizeh Marsh, southern of Iraq. Biodiversitas 22: 338-345. In order to describe the degree of contamination of aquatic environments in Iraq, heavy metals analysis (Fe, Ni, Cr, Cd, Pb, and Zn) was conducted for six aquatic macrophytes from different locations of Al-Hawizeh Marsh in southern Iraq. The six species were Azolla filiculoides (floating plant), Ceratophyllum demersum, Potamogeton pectinatus, Najas marina (submerged plants), Phragmites australis, and Typha domingensis (emergent plants). The results indicate that cadmium, chromium, and iron concentrations in aquatic plants were above the World Health Organization (WHO). In contrast, zinc, copper, and lead were within the allowable limits. C. demersum and N. marina showed higher concentrations of heavy metal accumulation than the other aquatic plants. The concentration of heavy metals in plant tissues during the summer months was higher than in the different seasons. C. demersum and N. marina showed higher concentrations of heavy metal accumulation than the other aquatic plants. Heavy metal bioconcentration (BCF) was calculated to assess heavy metals bioaccumulation in the aquatic plants.

Aquatic macrophyte communities and environmental factors were studied at four Al-Hawizeh marsh sites from December 2017 until November 2018. Quantitative data from thirty species of aquatic plants were collected to investigate density, vegetation cover, biomass and their relationship to the environmental factors. For emerging plants, relative abundance reached the highest values (36%) than submerged and wet species, while free-floating plants produced the lowest value (17%).Physical and chemical properties have been studied including water temperature ranging from 11.3 ° C in January to 31.4 ° C in August, dissolved oxygen (DO)ranging from 1.88 mg/L in September to 10.5 mg / L in April, pH varied from 7.2 in June to 8.4 in December, electrical conductivity (EC μ.S/cm) differs from 2257 μ.S/cm in November to 6859 μ.S/cm in April. The results identified the highest percentages of vegetation cover reported during the summer, the lowest percentages revealed during the winter for all plant groups. The highest annual vegetation cover rates for submergent species achieved 52.54% by C.demersum, for free-floating plants 66.67% of S. polyrrhiza, for emergent plants 85.5% of P. australis, 41.62% of P. paspaloide for wet plants. Total mean biomass of plant groups showed the highest value of 844.02 (gm dry weight/m2) reported by emerging plants, the lowest value of 47.25 (gm dry weight / m2) by the wet plants. Thus, biomass values were correlated with the vegetation cover values for all plants.

The fish assemblage structure in Al-Huwaizah marsh, southern of Iraq was assessed. Fish samples collected monthly by different fishing means from period December 2017 to November 2018. A total of 28959 individual of fish belonging to 9 families and 19 species were collected, 11 of them of native species and 8 of alienspecies. The numerical dominance index value (D3) of the highest three abundant species comprised 74.26% of the total fish caught, included Planiliza abu (Al-Keshny) 38.2% ; Coptodon zilli (Tilapia red abdomen) 29.41% and Carassius auratus (Prussian carp) 6.65%. The total weight of fish caught 2,190,680 tan, highest weight 312,242kg achieved in July, while lowest weight 41,590 kg found in September. The weight dominance index value (D3) of the highest three species in weight recorded 1,409,973 tan of the total weight of fish caught included C. zilli(Tilapia red abdomen) 659,994 kg , S. triostegus (Jerry fresh water) 495,784 kg and O. aureus (Blue tilapia) 245,195kg.The annual rate value for diversity, richness and evenness indices amounted 1.88, 1.75 and 0.64, respectively. Some of physical and chemical properties were studied such as water temperature which ranged from 11.5°C in January to 31.02°C in August month, dissolved oxygen ranged from 2.24 mg/l in September to 9.9mg/l in February, salinity varied from 1.37‰ in November to 3.76‰ in September and pH which ranged from 7.4 in June to 8.15 in December.Jaccard Similarity Index (Ss%) was used to know the similarity degree between the monthly catch samples. Also associations between distribution of fish species and the environmental variables were quantified by using canonical correspondence analysis (CCA).

Phytoplankton assemblage in relation to physical and chemical characteristics of water in Al-Auda marsh of Maysan province southern Iraq was assessed from November 2012 to July 2013. Six sampling sites were chosen to examine all phytoplankton species in the study area. A total of 246 species and seventy-five genera have been recognized belonging to twelve phytoplankton classes as follows: Bacillariophyceae (106 taxa), Chlorophyceae (34 taxa), Euglenophyceae (29 taxa), Cyanophyceae (29 taxa), Conjugatophyceae (19 taxa), Mediophyceae (10 taxa), Cryptophyceas (5 taxa), Coscinodiscophyceae (4 taxa), Chrysophyceae (4 taxa), Dinophyceae (3 taxa), Trebouxiophyceae (2 taxa) whereas Compsopogonophyceae recorded only (one taxon).The finding showed class Bacillariophyceae dominated with (43.09%), followed by Chlorophyceae of (13.82%), then (11.79%) for each of Cyanophycean and Euglenophyceae. Mean ± standard deviation for water temperature was ranged between (14.3±1.6°C) during winter to (35.6±1.81°C) during summer, electrical Conductivity (2020±186μ.s/cm) during autumn to (6390±875μ.s/cm) during summer, total Phosphate 0.01±0.0 µg/l during winter to 0.3±0.08 µg/l during spring, and total nitrogen varied from 1.8±0.8 µg/l during winter to 6.9±0.5 µg/l during autumn. Seasonal distribution indicated that phytoplankton flourished predominantly during the summer and spring. The diversity index (H) recorded the highest value in spring and lowest value in autumn, Richness (D) and Evenness (E) indices achieved the highest values in spring, the lowest values in autumn. The Jaccard index (Ss%) recorded the highest similarity between autumn and winter, the lowest similarity was between autumn and spring. The results revealed Al-Auda marsh is mesotrophic according to phytoplankton composition.